The long term objective of this proposal is to understand how macrophages and certain cytokines interact with tumor cells and affect their growth. Understanding this interaction will enhance immunotherapeutic approaches aimed at tumor destruction and growth inhibition. Three specific aims are proposed to address this objective in the murine tumor, line 1(L1): to characterize the in vivo role of con A-induced and thioglycollate-induced macrophages in the immunogenicity/of L1 cells and to assess the effect of these cells on subsequent immunity; 2) to evaluate the direct effects of TNF and IFN on L1 growth both in vivo and in vitro and to assess their effects on subsequent immunity in vivo; nd 3) to determine the role of macrophages and cytokines in tumor angiogensis. The experiments designed to achieve these aims will be done both in vivo and in vitro. To assess the role of macrophages, a Winn- like assay will be used which combines macrophages induced in the peritoneal cavity of mice by either Con A or thioglycollate with a L1 challenge. To determine what specific role the macrophages play in L1 tumor growth: 1) paraformaldehyde fixation will be used to distinguish antigen presentation from cytokine release, 2) irradiation of host mice will examine macrophage host -immune interaction and 3) surviving mice will be rechallenged to test for induce immunologic memory. To assess the role of TNF and IFN on tumor growth, the effect of these cytokines will be tested individually and in combination with a L1 challenge in immunocompetent and irradiated mice. Cytokine dosages for each condition will be determined for maximum effect. Surviving mice will be rechallenged to test for immunologic memory. The direct effects of TNF and Ifn on L1 cell growth in vitro will be assessed by growth in soft agar and 3H-thymidine incorporation assays. To assess the role of angiogensis in tumor growth and the effect macrophages and cytokines have on this process, the chorio- allantoic membrane (CAM) of chicks embryos will be used in preliminary studies and intradermal injections of mice will be used in the more definitive experiments. The CAM will allow optimal doses to be determined for both the cytokines and macrophages, and the mouse angiogenesis experiments will allow quantitation of the response in a syngeneic host.